Tuberculosis yield among contacts of non-pulmonary bacteriologically confirmed index TB patients in the urban setting of central Uganda

BACKGROUND: The World Health Organization (WHO) recommends systematic and active investigation of TB contacts. However, lower priority is given to contact investigation among other non-pulmonary bacteriologically confirmed (PBC) cases; it thus contributes to the scarce information on the yield of TB among contacts of index TB patients without microbiological confirmation (non-PBC patients). This study therefore aimed at establishing the yield of TB among contacts of PBC and non-PBC index TB patients in the urban setting of central Uganda. METHODS: We abstracted data from the Uganda national TB contact investigation registers present at 48 health facilities for the period January 2018 to August 2020. The screening yield for both PBC and non-PBC, timing of TB diagnosis among contacts were determined. Logistic regression was used to examine predictors for diagnosing contacts as non PBC TB patients. RESULTS: From January 2018 to August 2020, 234 persons were diagnosed with TB from a total of 14,275 contacts traced for both PBC and non-PBC TB index patients at 48 facilities. Of these, 100(42.7%) were contacts of non-PBC index patients. TB screening yield was higher among contacts of non PBC 100(2.0%) compared to 134(1.4%) among contacts of PBC index patients. For both groups, over 80% of their contacts were diagnosed with TB within 3 months from the day of TB treatment start of the index case. On multivariate logistic regression the only predictor for diagnosing contacts as non PBC TB patients was age under15 years (adjusted odds ratio [aOR] 7.53, 95% CI [3.27–17.3] p = <0.05). CONCLUSION: The yield of TB among contacts of non-PBC index case is nearly the same for contacts of PBC index cases and most contacts were diagnosed with TB disease during the intensive TB treatment phase of the index case. There was no association between the type of TB (PBC, non-PBC) disease diagnosed in the contacts, and that of index TB patients. To improve TB case-finding, emphasis should be placed on contact investigation for household and close contacts of all other index cases with pulmonary tuberculosis regardless of whether PBC or non-PBC during the intensive phase of treatment.